Apparatus for injecting gas into a vessel

ABSTRACT

An apparatus for injecting particulate and/or gaseous material into a metallurgical vessel is disclosed. The apparatus includes a duct through which to inject the material, inner and outer water inflow and outflow passages extending through a wall of the duct and an annular duct tip disposed at the forward end of the duct. The duct tip is of annular formation and includes an annular inner end component, an annular outer end component, and an annular central component located between the inner and outer components. The duct tip also includes a plurality of radially extending dividers to divide a space between the outer end component and the central component into discrete radial passages to serve as the internal water flow passages of the tip.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.60/874,979, filed Dec. 15, 2006, the content of which is incorporatedherein by reference.

The present invention provides an apparatus for injecting gas into avessel. It has particular, but not exclusive application to apparatusfor injecting a flow of gas into a metallurgical vessel under hightemperature conditions. Such metallurgical vessel may for example be asmelting vessel in which molten metal is produced by a direct smeltingprocess.

A known direct smelting process, which relies on a molten metal layer asa reaction medium, and is generally referred to as the Hlsmelt process,is described in U.S. Pat. No. 6,083,296. The HIsmelt process asdescribed in that Patent comprises:

-   -   (a) forming a bath of molten iron and slag in a vessel;    -   (b) injecting into the bath:    -   (i) a metalliferous feed material, typically metal oxides; and    -   (ii) a solid carbonaceous material, typically coal, which acts        as a reductant of the metal oxides and a source of energy; and    -   (c) smelting metalliferous feed material to metal in the metal        layer.

The term “smelting” is herein understood to mean thermal processingwherein chemical reactions that reduce metal oxides take place toproduce liquid metal.

The HIsmelt process also comprises post-combusting reaction gases, suchas CO and H₂ released from the bath in the space above the bath withoxygen-containing gas and transferring the heat generated by thepost-combustion to the bath to contribute to the thermal energy requiredto smelt the metalliferous feed materials.

The HIsmelt process also comprises forming a transition zone above thenominal quiescent surface of the bath in which there is a favourablemass of ascending and thereafter descending droplets or splashes orstreams of molten metal and/or slag which provide an effective medium totransfer to the bath the thermal energy generated by post-combustingreaction gases above the bath.

In the HIsmelt process the metalliferous feed material and solidcarbonaceous material is injected into the metal layer through a numberof lances/tuyeres which are inclined to the vertical so as to extenddownwardly and inwardly through the side wall of the smelting vessel andinto the lower region of the vessel so as to deliver the solids materialinto the metal layer in the bottom of the vessel. To promote the postcombustion of reaction gases in the upper part of the vessel, a blast ofhot air, which may be oxygen enriched, is injected into the upper regionof the vessel through the downwardly extending hot air injection lance.To promote effective post combustion of the gases in the upper part ofthe vessel, it is desirable that the incoming hot air blast exit thelance with a swirling motion. To achieve this, the outlet end of thelance may be fitted with internal flow guides to impart an appropriateswirling motion. The upper regions of the vessel may reach temperaturesof the order of 2000° C. and the hot air may be delivered into the lanceat temperatures of the order of 1100-1400° C. The lance must thereforebe capable of withstanding extremely high temperatures both internallyand on the external walls, particularly at the delivery end of the lancewhich projects into the combustion zone of the vessel.

U.S. Pat. No. 6,440,356 discloses a gas injection lance constructiondesigned to meet the extreme conditions encountered in the HIsmeltprocess. In that construction, the flow guides are in the form of spiralvanes mounted on a central body at the forward end of a gas flow duct.Those vanes are connected to the wall of the gas flow duct and areinternally water cooled by cooling water which flows through supply andreturn passages within the wall of the duct. U.S. Pat. No. 6,673,305discloses an alternative lance construction in which spiral flow guidevanes are mounted on a central tubular structure extending throughoutthe length of the gas flow duct. The central structure is provided withwater flow passages which provide for the flow of cooling water to thefront part of the central structure which is located generally withinthe tip of the gas flow duct. In that construction, the flow guide vanesare not cooled and are set back from the tip of the duct within arefractory lined wall section of the duct.

In the constructions disclosed in U.S. Pat. Nos. 6,440,356 and 6,673,305the tip of the duct is formed with a single annular space through whichcooling water flows from the delivery passages to the return passages inthe duct wall passages are of similar length. The present inventionprovides an improved construction which enables more effective coolingof the tip and improved structural strength. The invention may also beapplied to the solids injection lances for injecting solid particulatematerial into the vessel.

According to the invention there is provided an apparatus for injectingparticulate and/or gaseous material into a metallurgical vessel forperforming a metallurgical process, the apparatus comprising

a duct through which to inject the material;;

inner and outer water inflow and outflow passages extending through awall of the duct respectively for inflow of cooling water from a rearend to a forward end of the duct and for outflow of cooling water fromthe forward end to the rearward end of the duct; and

an annular duct tip disposed at the forward end of the duct andproviding a water flow connection between the inner and the outer waterflow passages; and

wherein the duct tip is of annular formation and comprised of an annularinner end component, an annular outer end component, an annular centralcomponent located between the inner and outer components, and aplurality of radially extending dividers to divide a space between theouter end component and the central component into discrete radialpassages to serve as said internal water flow passages of the tip.

The duct may be a gas flow duct for discharge of gas flow from theforward end of the duct.

The dividers may be in the form of ribs on the outer end component.

The central component may have a series of radial grooves to receive atleast some of the ribs on the outer end component.

The ribs on the outer end component may comprise a first series of ribsspaced circumferentially of the outer end component and a second seriesof ribs spaced circumferentially of the outer end component between theribs of the first series, the ribs of the first series projecting fromthe outer end component further than the ribs of the second series andbeing received by the series of grooves in the central component.

The ribs of the first series may be welded to the central component ofthe tip.

The ribs of the second series may abut the central component of the tipbetween the ribs of the first series.

The space between the outer end component of the tip and the centralcomponent which is divided by the ribs into said discrete water flowpassages may progressively narrow in the radially outward directionsalong the passages.

The inner, outer and central components of the tip may be made of thesame material and may be welded together. They may for example be formedof copper and that copper may be at least 99% pure to promote effectiveand even heat transfer through the tip.

The wall of the material injection duct may be comprised ofconcentrically spaced apart inner, intermediate and outer tubes forminginner and outer annular spaces subdivided into the inner and outer waterflow passages.

The inner annular space may be subdivided into the inner water flowpassages for water inflow by inner divider bars extending spirallyaround and welded to the outer peripheral surface of the inner duct tubeand flush fitted within the intermediate duct tube.

The outer annular space may be subdivided into the outer water flowpassages for water outflow by outer divider bars extending spirallyaround and welded to the outer peripheral surface of the intermediateduct tube and flush fitted within the outer duct tube.

The inner annular space may be wider in the radial direction than theouter annular space and the inner divider bars may be correspondinglytaller in the radial direction than the outer divider bars.

According to the invention there is also provided a direct smeltingvessel that is fitted with the above-described apparatus for injectingmaterial into the vessel.

According to the invention there is also provided an apparatus forinjecting particulate and/or gaseous material into a metallurgicalvessel for use in a metallurgical process, the apparatus comprising

a duct through which to inject said material comprising a duct wall ofconcentric annular passages for in flow of cooling water from a rear endto a forward end of the duct along a first of said annular passages andfor outflow of cooling water from the forward end to the rear end of theduct wall along a second of said annular passages;

said concentric annular passages provided by concentric sleevesconsisting of an inner sleeve, an outer sleeve and an intermediatesleeve;

a duct tip at a forward end of the duct joining at least the inner andouter sleeves so as to provide a water flow connection between the firstand second water flow passages;

said outer sleeve providing at least a part of an outer surface of saidapparatus and having a rear portion of greater diameter than a forwardportion;

said intermediate sleeve having a rear portion of greater diameter thana forward portion and said rear portion of said intermediate sleevedisposed adjacent said rear portion of said outer sleeve; and

said rear portion of said outer sleeve and said rear portion of saidintermediate sleeve configured such that the radial width of the annularpassage provided between the outer sleeve and the intermediate sleeveadjacent the rear portion of the outer sleeve is generally the same asthe radial width of the annular passage provided between the outersleeve and the intermediate sleeve adjacent the forward portion of theouter sleeve.

The wall thickness of the rear portion of the outer sleeve may begenerally the same as the wall thickness of the forward portion of theouter sleeve and the wall thickness of the rear portion of theintermediate sleeve may be greater than the wall thickness of theforward portion of the intermediate sleeve.

The apparatus may comprise a further sleeve member disposed adjacent theouter surface of the intermediate sleeve to thereby provide said greaterdiameter of said rear portion of said intermediate sleeve.

The further sleeve member may be spaced inwardly of and suspended from arear portion of said apparatus so as to provide at least one water flowgallery for said inflow or said outflow of water to said duct wall.

The apparatus may comprise a housing member that connects a rear end ofsaid inner sleeve with said rear end of said outer sleeve and wherein arear portion of said intermediate sleeve is disposed inwardly of an endof said housing to thereby provide a water flow path rearwardly of saidintermediate sleeve.

The further sleeve member may be disposed forwardly of said rear portionof said intermediate sleeve so as to divide a rear portion of saidapparatus into first and second water flow galleries for inflow andoutflow of water to said annular passages.

The further sleeve member may be secured to said rear portion of saidapparatus and a sliding seal is provided intermediate said furthersleeve member and said intermediate sleeve so as to permit relativelongitudinal movement of said intermediate sleeve and said furthersleeve member.

A rear portion of said intermediate sleeve may be comprised of a firstportion extending rearwardly of said further sleeve member and a secondportion extending forwardly from said further sleeve member to said ducttip and a sliding seal may be provided between said second portion ofsaid intermediate sleeve and said further sleeve member.

An internal surface of said intermediate sleeve and an external surfaceof said inner sleeve may be separated by at least one dividing barextending in a spiral arrangement therebetween.

The first portion of said intermediate sleeve may be secured to said atleast one dividing bar.

The inner diameter of the intermediate sleeve may be generally constant.

The external surface of the inner sleeve may be generally constantwhereby the radial thickness of the water flow passage disposed betweensaid inner sleeve and said intermediate sleeve may be generally constantalong its length.

An internal surface of said outer sleeve and an external surface of saidintermediate sleeve may be separated by at least one dividing barextending in a spiral arrangement therebetween.

In order that the invention may be more fully explained, embodimentswill be described in some detail with reference to the accompanyingdrawings in which:

FIG. 1 is a vertical section through a direct smelting vesselincorporating one embodiment of a hot air injection lance constructed inaccordance with the invention;

FIG. 2 is a longitudinal cross-section through the hot air injectionlance;

FIG. 3 is a side elevation of a forward part of another embodiment ofthe lance;

FIG. 4 is an end elevation of the forward part of the lance shown inFIG. 3;

FIG. 5 is a longitudinal cross-section through the forward part of thelance shown in FIG. 3;

FIG. 6 is an enlargement of a forward part of the lance of FIG. 5showing the construction of a lance tip—noting that the lance tip of thelance shown in FIG. 2 has the same construction;

FIG. 7 is a cross-section on the line 7-7 in FIG. 6;

FIG. 8 illustrates an inner end component of the annular tip of thelance;

FIG. 9 is a cross-section on the line 9-9 in FIG. 8;

FIG. 10 illustrates an outer end component of the lance tip;

FIG. 11 is a perspective view of an inner face of the component shown inFIG. 10;

FIG. 12 is a diagrammatic side view of the component illustrated in FIG.10;

FIG. 13 is a cross-section on the line 13-13 in FIG. 10;

FIG. 14 is a cross-section on the line 14-14 in FIG. 10;

FIG. 15 is a cross-section on the line 15-15 in FIG. 10;

FIG. 16 illustrates a central component of the duct tip;

FIG. 17 is a side elevation of the tip component illustrated in FIG. 16;and

FIG. 18 is a cross-section on the line 18-18 in FIG. 16.

FIG. 1 illustrates a direct smelting vessel suitable for operation bythe HIsmelt process as described in U.S. Pat. No. 6,083,296. Themetallurgical vessel is denoted generally as 11 and has a hearth thatincludes a base 12 and sides 13 formed from refractory bricks; sidewalls 14 which form a generally cylindrical barrel extending upwardlyfrom the sides 13 of the hearth and which includes an upper barrelsection 15 and a lower barrel section 16; a roof 17; an outlet 18 foroff-gases; a forehearth 19 for discharging molten metal continuously;and a tap-hole 21 for discharging molten slag.

In use, the vessel contains a molten bath of iron and slag whichincludes a layer 22 of molten metal and a layer 23 of molten slag on themetal layer 22. The arrow marked by the numeral 24 indicates theposition of the nominal quiescent surface of the metal layer 22 and thearrow marked by the numeral 25 indicates the position of the nominalquiescent surface of the slag layer 23. The term “quiescent surface” isunderstood to mean the surface when there is no injection of gas andsolids into the vessel.

The vessel is fitted with a downwardly extending hot air injection lance26 for delivering a flow of air at a temperature in the order of 1200°C, so-called “hot air blast”, into an upper region of the vessel andsolids injection lances 27 extending downwardly and inwardly through theside walls 14 and into the slag layer 23 for injecting iron ore, solidcarbonaceous material, and fluxes entrained in an oxygen-deficientcarrier gas into the metal layer 22. The position of the lances 27 isselected so that their outlet ends 28 are above the surface of the metallayer 22 during operation of the process. This position of the lancesreduces the risk of damage through contact with molten metal and alsomakes it possible to cool the lances by forced internal water coolingwithout significant risk of water coming into contact with the moltenmetal in the vessel.

The construction of different embodiments of the hot air injection lance26 is illustrated in FIGS. 2 to 18. FIG. 2 depicts a first embodimentand FIGS. 3-5 depict a second embodiment. Equivalent components have thesame numbering in FIGS. 2-5. The lance tip shown in FIGS. 6-18 isdescribed in the contest of the second embodiment of the lance shown inFIGS. 3-5. The lance tip shown in FIG. 2 has the same construction.

Referring now to FIG. 2 lance 26 comprises an elongate duct 31 whichreceives hot gas through a gas inlet structure 32 and injects it intothe upper region of vessel. An annular duct tip 36 is disposed at theforward end of the gas flow duct 31. The lance includes an elongatecentral tubular structure 33 which extends within the gas flow duct 31from its rear end to its forward end. Adjacent the forward end of theduct, central structure 33 carries a series of swirl imparting vanes 34for imparting swirl to the gas flow exiting the duct. Swirl vanes 34 maybe formed to a four start helical configuration. Their inlet (rear) endsmay have a smooth transition from initial straight sections to a fullydeveloped helix to minimise turbulence and pressure drop.

The forward end of central structure 33 has a domed nose 35 whichprojects forwardly beyond the tip 36 of duct 31 so that the forward endof the central body and the duct tip co-act together to form an annularnozzle for divergent flow of gas from the duct with swirl imparted bythe vanes 34.

The wall of the main part of duct 31 extending downstream from the gasinlet 32 is internally water cooled. This section of the duct iscomprised of a series of three concentric steel tubes 37, 38, 39extending to the forward end part of the duct where they are connectedto the duct tip 36.

In the second embodiment as depicted in FIGS. 3-5 outer tube 39 isstepped at 39A so that the rear part 39B of that tube is of greaterdiameter than the forward part 39C. The rear part of intermediate tube38 is thickened by an external sleeve 40 disposed within the rearportion 39B of the outer tube 39. An inner annular space 41 of constantradial width is defined between the tubes 37, 38 and an outer annularspace 42 of a smaller constant radial width is defined between the tubes38, 39, both spaces 41, 42 extending back from the tip through to therear part of the duct with the outer annular space 42 extendingoutwardly and back along the enlarged diameter rear portion 39B of theouter tube 39. The annular spaces 41, 42 are subdivided into inner andouter water flow passages by spirally extending inner divider bars 43and outer spirally extending divider bars 44 respectively to form aseries of four spirally extending inner flow passages 45 and a secondseries of four spirally extending outer flow passages 46.

Cooling water is supplied to the inner passages 45 through two waterinlets 47 and an annular inlet manifold 48 at the rear end of the duct.The water flows forwardly along the spiral passages 45 to the tip 36through which it flows in the manner to be described later in thisspecification back into the outer spirally extending passages 46 alongwhich it flows back to the rear end of the duct to exit through anoutlet manifold 49 and two water outlets 51.

The inner water flow passages 45 extend in a four-start helical array.The outer water flow passages 46 also extend in a four-start helicalarray but at a much shorter pitch than the spiral inner passages 45.More specifically the inner passages 45 extend through onlyapproximately one quarter of a turn in extending from the rear end tothe rear end of the duct to the tip whereas the outer return passages 46extend at a much shorter pitch through several turns in the distancefrom the tip back to the outlet manifold 49. This increases theresidence time of the water within the outer passages 46 to enhancecooling of the outer parts of the duct. The radial width of the innerpassages 45 is greater than the radial width of the outer passages 46and the water flow is accelerated as it flows through the tip to enhanceheat extraction through the tip, a constant volumetric flow beingmaintained through the narrower outer flow passages 46.

The inner divider bars 43 extend spirally around and are welded to theouter peripheral surface of the inner duct tube 37 and flush fittedwithin the intermediate tube 38. The outer divider bars 44 forming theouter flow passages extend spirally around and are welded to the outerperipheral surface of the intermediate tube 38 (including the thickenedrear portion 39B of the second embodiment) and flush fitted within theouter duct tube 39 (including the enlarged diameter rear portion 39B ofthat tube).

The rear end of duct tube 39 is connected to a tubular housing 52 whichreceives the rear ends of the inner and intermediate tubes 37, 38 andcarries the water inlets 47 and outlets 51.

External sleeve 40 is disposed inwardly of and secured to tubularhousing 52. This divides the rear portion of the lance into two waterflow galleries, one for inflow of water 48 and one for outflow of water49.

The intermediate tube 38 is located inwardly of an end wall of saidhousing 52 to provide a flow path from gallery 48 to inner passage 45.

Housing 52 is provided with a rear flange 53 for connection to a gasinlet structure, such as inlet structure 32 in the first embodiment.Flange 53 is also connected to a mounting flange 54 for connection ofthe lance with a vessel. In the first embodiment, flange 54 suspends thelance in a vertical orientation within the vessel with all of its weighttaken through the outer duct tube 39.

The second embodiment may be suspended at an angle to the vertical, withthe larger diameter portion 39B providing a mounting sleeve for locationin mounting nozzles positioned on a vessel. Typically, in a vessel ofthe type depicted in FIG. 1, a number of such nozzles, would be locatedon roof 17 and lances of the type depicted in the second embodimentwould replace lance 26 depicted in FIG. 1. Typically the large diameterportion 39B has a length of between one quarter and one half of thelength of the lance.

The rear end of the intermediate tube 38 is supported by a sliding seal55 within housing 52 to permit relative longitudinal movements of thetubes on differential expansion of the various lance components. Inparticular, intermediate tube 38 may be separated into a first portionextending rearwardly of the lance and secured to spiral dividing bars43. A second portion of intermediate tube 38 extends forwardly to theduct tip.

The water cooled duct 31 is internally lined with internal refractorylining 56 that fits within the inner tube 39 of the duct and extendsthrough to the water cooled tip 36 of the duct. The inner periphery ofthe duct tip 36 is generally flush with the inner surface of therefractory lining which defines the effective flow passage for gasthrough the duct.

The outer peripheral surface 56 of the forward part of outer tube 39,which in the second embodiment is between the step 39A and the tip 36,may be roughened or provided with projections to serve as keyingformations to promote accretion of slag on that surface, the slagserving as a protective layer against over-heating of that surface.

Duct tip 36 is of annular formation and is comprised of an annular innerend component 61 an annular outer end component 62 and an annularcentral component 63 located between the inner and outer components. Theouter end component 62 is provided with a plurality of radiallyextending ribs to divide the space between that outer end component 62and the central component 63 into discrete radial passages 64 for flowof water around the tip as it flows from the spiral inflow passages 45to the spiral outflow passages 46. The ribs on the outer end component62 comprise a first series of ribs 65 spaced circumferentially of theouter end component and a second series of ribs 66 spacedcircumferentially of the outer end component between the ribs 65 of thefirst series. The ribs 65 of the first series project from the outercomponent further than the ribs 66 of the second series. The centralcomponent 63 is provided with a series of radial grooves 67 to receivethe ribs 65 of the first series, the shallower ribs of the second seriesmerely abutting the central component 63 of the tip between the tallerribs 65 interfitted into the grooves 67. Outer end parts of the tallerribs 65 are welded at locations 68 to the central component 63 to firmlyfix the outer and central components 62, 63 together with the ribs 65,66 subdividing a space between them into the discrete water flowpassages 64. The space 69 between the inner tip component 61 and thecentral component 63 is undivided and so provides a single inwardlydirected annular flow path from the inflow passages 45 to the discretetip passages 64 which extend radially outwardly and back around theouter part of the tip toward the outflow passages 46. The space betweenthe outer end components 62 and the central components 63 which isdivided by the ribs 65, 66 into the discrete water flow passages 64narrows in the radially outward directions along the passages so thatthe passages 64 decrease in effective cross-section in the radiallyoutward direction to accelerate the cooling water as it flows throughthe tip.

The inner outer and central components 61, 62, 63 of the tip are weldedtogether and are all made of a high purity copper so as to promoteeffective and even heat transfer through the tip and to avoid anymovement between the components due to differential thermal expansionwhich might otherwise affect the formation and size of the discretewater flow passages through the tip.

Although the illustrated embodiment of the invention is a gas injectionlance it will be appreciated that the annular duct tip, could also beemployed on solids injection lances, for example lances of the generalconstruction disclosed in International Application PCT/AU2005/001603.It is accordingly to be understood that the invention is not limited tothe constructional details of the illustrated embodiments and that manyvariations will fall within its scope.

By way of example, whist the embodiments of the lance are described ashot air injection lances, the invention is not so limited and extends toinjection of any suitable gas and to injection of particulate material.By way of example, injected particulate material may include iron orefines and/or carbonaceous material.

1. An apparatus for injecting particulate and/or gaseous material into ametallurgical vessel for performing a metallurgical process, theapparatus comprising a duct through which to inject the material; innerand outer water passages extending through a wall of the ductrespectively for inflow of cooling water from a rear end to a forwardend of the duct and for outflow of cooling water from the forward end tothe rear end of the duct; and an annular duct tip disposed at theforward end of the duct and providing a water flow connection betweenthe inner and the outer water flow passages; and wherein the duct tiphas an annular inner end component, an annular outer end component, anannular central component located between the inner and outer endcomponents, and a plurality of radially extending dividers, which aredisposed radially with respect to the duct and are spacedcircumferentially within the duct tip, and which divide a space betweenthe outer end component and the central component into discrete radialpassages to serve as internal water flow passages through which water isto flow radially with respect to the annular duct tip.
 2. The apparatusdefined in claim 1 wherein the material injection duct is a gas flowduct for discharge of gas flow from the forward end of the duct.
 3. Theapparatus defined in claim 1 or claim 2 wherein the radially extendingdividers are in the form of ribs on the outer end component.
 4. Theapparatus defined in claim 3 wherein the central component has a seriesof radial grooves to receive at least some of the ribs on the outer endcomponent.
 5. The apparatus defined in claim 4 wherein the ribs on theouter end component comprise a first series of ribs spacedcircumferentially within the outer end component and a second series ofribs spaced circumferentially within the outer end component between theribs of the first series, and wherein the ribs of the first seriesproject from the outer end component further than the ribs of the secondseries and are received by the series of radial grooves in the centralcomponent.
 6. The apparatus defined in claim 5 wherein the ribs of thefirst series are welded to the central component.
 7. The apparatusdefined in claim 5 wherein the ribs of the second series abut thecentral component between the ribs of the first series.
 8. The apparatusdefined in claim 3 wherein the space between the outer end component andthe central component which is divided by the ribs into said discreteradial passages progressively narrows in the radially outward directionwith respect to the annular duct tip.
 9. The apparatus defined in claim1 wherein the inner end component, outer end component and centralcomponent are made of the same material and are welded together.
 10. Theapparatus defined in claim 9 wherein each of the inner end component,outer end component and central component of the tip are formed ofcopper.
 11. The apparatus defined in claim 1 wherein the wall of thematerial injection duct is comprised of concentrically spaced apartinner, intermediate and outer tubes forming inner and outer annularspaces subdivided into the inner and outer water flow passages.
 12. Theapparatus defined in claim 11 wherein the inner annular space issubdivided into the inner water flow passages for water inflow by innerdivider bars extending spirally around and welded to the outerperipheral surface of the inner duct tube and flush fitted within theintermediate duct tube.
 13. The apparatus defined in claim 11 or claim12 wherein the outer annular space is subdivided into the outer waterflow passages for water outflow by outer divider bars extending spirallyaround and welded to the outer peripheral surface of the intermediateduct tube and flush fitted within the outer duct tube.
 14. The apparatusdefined in claim 11 wherein the inner annular space is wider in theradial direction than the outer annular space and the inner divider barsis correspondingly taller in the radial direction than the outer dividerbars.
 15. A direct smelting vessel that is fitted with the apparatus forinjecting material into the vessel defined in claim
 1. 16. The apparatusdefined in claim 1, wherein the duct comprises a duct wall of concentricannular passages for inflow of cooling water from a rear end to aforward end of the duct along a first of said annular passages and foroutflow of cooling water from the forward end to the rear end of theduct wall along a second of said annular passages; said concentricannular passages provided by concentric sleeves consisting of an innersleeve, an outer sleeve and an intermediate sleeve, and the duct tipjoining at least the inner and outer sleeves so as to provide a waterflow connection between the inner and outer water flow passages.
 17. Theapparatus defined in claim 16, wherein said outer sleeve provides atleast a part of an outer surface of said apparatus and having a rearportion of greater diameter than a forward portion; said intermediatesleeve having a rear portion of greater diameter than a forward portionand said rear portion of said intermediate sleeve disposed adjacent saidrear portion of said outer sleeve; and said rear portion of said outersleeve and said rear portion of said intermediate sleeve configured suchthat the radial width of the annular passage provided between the outersleeve and the intermediate sleeve adjacent the rear portion of theouter sleeve is generally the same as the radial width of the annularpassage provided between the outer sleeve and the intermediate sleeveadjacent the forward portion of the outer sleeve.
 18. The apparatus asclaimed in claim 17 wherein a wall thickness of the rear portion of theouter sleeve is generally the same as a wall thickness of the forwardportion of the outer sleeve, and a wall thickness of the rear portion ofthe intermediate sleeve is greater than a wall thickness of the forwardportion of the intermediate sleeve.
 19. The apparatus as claimed inclaim 17 wherein a further sleeve member is disposed adjacent the outersurface of the intermediate sleeve to thereby provide said greaterdiameter of said rear portion of said intermediate sleeve.
 20. Theapparatus as claimed in claim 19 wherein said further sleeve member isspaced inwardly of and suspended from a rear portion of said apparatusso as to provide at least one water flow gallery for said inflow or saidoutflow of water to said duct wall.
 21. The apparatus as claimed inclaim 20 wherein a housing member connects a rear end of said innersleeve with said rear end of said outer sleeve and wherein the rearportion of said intermediate sleeve is disposed inwardly of an end ofsaid housing to thereby provide a water flow path rearwardly of saidintermediate sleeve.
 22. The apparatus as claimed in claim 21 whereinsaid further sleeve member is disposed forwardly of said rear portion ofsaid intermediate sleeve so as to divide the rear portion of saidapparatus into first and second water flow galleries for inflow andoutflow of water to said annular passages.
 23. The apparatus as claimedin claim 22 wherein said further sleeve member is secured to said rearportion of said apparatus and a sliding seal is provided intermediatesaid further sleeve member and said intermediate sleeve so as to permitrelative longitudinal movement of said intermediate sleeve and saidfurther sleeve member.
 24. The apparatus as claimed in claim 23 whereinthe rear portion of said intermediate sleeve is comprised of a firstportion extending rearwardly of said further sleeve member and a secondportion extending forwardly from said further sleeve member to said ducttip and the sliding seal is provided between said second portion of saidintermediate sleeve and said further sleeve member.
 25. The apparatus asclaimed in claim 24 wherein an internal surface of said intermediatesleeve and an external surface of said inner sleeve are separated by atleast one dividing bar extending in a spiral arrangement therebetween.26. The apparatus as claimed in claim 25 wherein said first portion ofsaid intermediate sleeve is secured to said at least one dividing bar.27. The apparatus as claimed in claim 16 wherein an inner diameter ofthe intermediate sleeve is generally constant.
 28. The apparatus asclaimed in claim 27 wherein an external surface of the inner sleeve isgenerally constant whereby a radial thickness of the water flow passagedisposed between said inner sleeve and said intermediate sleeve isgenerally constant along its length.
 29. The apparatus as claimed inclaim 16 wherein an internal surface of said outer sleeve and anexternal surface of said intermediate sleeve are separated by at leastone dividing bar extending in a spiral arrangement therebetween.
 30. Adirect smelting vessel that is fitted with the apparatus for injectingmaterial into the vessel defined in claim 29.